Eddie, That is a touchy, difficult, time consuming area to fit new parts. Without going through all of your posts, did you build a new boot cowl without windshield screw holes? If not you are needing to match the shape of the new windshield and the new strips to the old holes, that is a project. If the windshield isn't cut and shaped exactly the same as the old one you will never get the new strips to match up with the screw holes. Even when fitting all new there is a lot of cutting, fitting, stretching and shrinking to get it to all fit nicely. I'm not sure that the Javron parts would fit any better than the Univair ones which you already have.
When I put my Cub together I started at the forward center working both sides a little at a time until back to the door post. First the windshield lower edge, then the rear strip followed by the front strip. I have no idea of how many times all of the pieces went on and off. It was very time consuming. After all that was finished the top and sides were cut to size. Leave those cuts until last since they just hang over the edges and will not effect the fit of the windshield. Place a magic marker center point on the windshield top and bottom so that it goes on in the exact same location each time. Keep all of your cuts in the plexiglass smooth so that you don't get a crack started while working it. Plexi is brittle and can crack/break quickly and easily. Having warm temperatures is a big help.
As far as fiberglass for the strip, I'm not sure about the legality since Piper used aluminum. This could not be considered as "owner produced" since it would not be to the original specs.